Design of achromatic surface microstructure for near-eye display with diffractive waveguide

Dispersion problem has always constrained the development of see-through near-eye displays with diffractive waveguide. Here, we propose a design method and optical systems for one-layer achromatic surface microstructure composed with a triple-carved-sub-grating. The triple-carved-sub-grating with specified period is designed based on rigorous coupled wave theory, corresponding to Red (R), Green (G) and Blue (B) wavelengths, respectively. The surface microstructure with period of 18.9um is realized by synthesizing the three subgratings together, and it is verified numerically that the diffractive angle of R, G, and B wavelengths is 35 degrees under the normal incidence of TE polarization, which imply that the surface microstructure diffracts the certain RGB wavelengths achromatically. A diffraction waveguide with achromatic surface microstructure is also modeled to analysis the stray light and color correction, and the results indicate that the diffraction waveguide transmits image with little stray light. Via proper duplication it could be utilized as the combining optics of diffractive-waveguide near-eye display and head-up display because of its light and compact features.